#pragma once
#include "requestor.hpp"
#include <unordered_set>

namespace rpc {
    namespace client {
        class Provider {
        public:
            using ptr = std::shared_ptr<Provider>;
            Provider(const Requestor::ptr& requestor)
                :_requestor(requestor)
            {}

            bool registryMethod(const BaseConnection::ptr& conn, const std::string& method, const Address& host) {
                auto msg_req = MessageFactory::create<ServiceRequest>();
                msg_req->setId(UUID::uuid());
                msg_req->setMType(MType::REQ_SERVICE);
                msg_req->setMethod(method);
                msg_req->setHost(host);
                msg_req->setOptype(ServiceOptype::SERVICE_REGISTRY);

                BaseMessage::ptr msg_rsp;
                bool ret = _requestor->send(conn, msg_req, msg_rsp);
                if(ret == false) {
                    // ELOG("%s 服务注册失败!", method.c_str());
                    return false;
                }

                auto service_rsp = std::dynamic_pointer_cast<ServiceResponse>(msg_rsp);
                if(service_rsp.get() == nullptr) {
                    // ELOG("响应类型向下转换失败!");
                    return false;
                }

                return true;
            }
        private:
            Requestor::ptr _requestor;
        };

        class MethodHost{
        public:
            using ptr = std::shared_ptr<MethodHost>;
            
            MethodHost()
                :_idx(0)
            {}

            MethodHost(const std::vector<Address>& hosts)
                :_hosts(hosts.begin(), hosts.end())
                ,_idx(0)
            {}

            void appendHost(const Address& host) {
                // 中途收到了服务上线请求后被调用
                std::unique_lock<std::mutex> lock(_mutex);
                _hosts.push_back(host);
            }

            void removeHost(const Address& host) {
                // 中途收到了服务下线请求后被调用
                std::unique_lock<std::mutex> lock(_mutex);
                for(auto it = _hosts.begin(); it != _hosts.end(); ++it) {
                    if(*it == host) {
                        _hosts.erase(it);
                        break;
                    }
                }
            }

            Address chooseHost() {
                std::unique_lock<std::mutex> lock(_mutex);
                size_t pos = _idx++ % _hosts.size();
                return _hosts[pos];
            }

            bool empty() {
                std::unique_lock<std::mutex> lock(_mutex);
                return _hosts.empty();
            }

        private:
            std::mutex _mutex;
            size_t _idx;
            std::vector<Address> _hosts;
        };

        class Discoverer {
        public:
            using OfflineCallback = std::function<void(const Address&)>;
            using ptr = std::shared_ptr<Discoverer>;

            Discoverer(const Requestor::ptr& requestor, const OfflineCallback& cb)
                :_requestor(requestor)
                ,_offline_callback(cb)
            {}

            bool serviceDiscovery(const BaseConnection::ptr& conn, const std::string& method, Address& host) {
                {
                    // 当前所保管的提供者信息存在，则直接返回地址
                    std::unique_lock<std::mutex> lock(_mutex);
                    auto it = _method_hosts.find(method);
                    if(it != _method_hosts.end()) {
                        if(it->second->empty() == false) {
                            host = it->second->chooseHost();
                            return true;
                        }
                    }
                }

                // 当前服务的提供者为空
                auto msg_req = MessageFactory::create<ServiceRequest>();
                msg_req->setId(UUID::uuid());
                msg_req->setMType(MType::REQ_SERVICE);
                msg_req->setMethod(method);
                msg_req->setOptype(ServiceOptype::SERVICE_DISCOVERY);
                
                BaseMessage::ptr msg_rsp;
                bool ret = _requestor->send(conn, msg_req, msg_rsp);
                if(ret == false) {
                    // ELOG("服务发现失败!");
                    return false;
                }
                auto service_rsp = std::dynamic_pointer_cast<ServiceResponse>(msg_rsp);
                if(!service_rsp) {
                    // ELOG("服务发现失败，响应类型转换失败!");
                    return false;
                }
                if(service_rsp->rcode() != RCode::RCODE_OK) {
                    // ELOG("服务发现失败! %s", errReason(service_rsp->rcode()).c_str());
                    return false;
                }
                // 能走到这里，代表当前是没有对应的服务提供主机的
                std::unique_lock<std::mutex> lock(_mutex);
                auto method_host = std::make_shared<MethodHost>(service_rsp->hosts());
                if(method_host->empty()) {
                    // ELOG("%s 服务发现失败! 没有能提供服务的主机!", method.c_str());
                    return false;
                }

                host = method_host->chooseHost();
                _method_hosts[method] = method_host;

                return true;
            }

            // 这个接口是提供给Dispatcher模块进行服务上线下线请求处理的回调函数
            void onServiceRequest(const BaseConnection::ptr& conn, const ServiceRequest::ptr& msg) {
                // 1.判断是上线还是下线请求，如果都不是那就不用处理了
                auto optype = msg->optype();
                std::string method = msg->method();
                std::unique_lock<std::mutex> lock(_mutex);
                if(optype == ServiceOptype::SERVICE_ONLINE) {
                    // 2.上线请求：找到MethodHost，想其中新增一个主机地址
                    auto it = _method_hosts.find(method);
                    if(it == _method_hosts.end()) {
                        auto method_host = std::make_shared<MethodHost>();
                        method_host->appendHost(msg->host());
                        _method_hosts[method] = method_host;
                    }
                    else {
                        it->second->appendHost(msg->host());
                    }
                }
                else if(optype == ServiceOptype::SERVICE_OFFLINE) {
                    // 3.下线请求：找到MethodHost，从其中删除一个主机地址
                    auto it = _method_hosts.find(method);
                    if(it == _method_hosts.end()) {
                        return;
                    }
                    it->second->removeHost(msg->host());
                    _offline_callback(msg->host());
                }
            }
        private:
            OfflineCallback _offline_callback;
            std::mutex _mutex;
            std::unordered_map<std::string, MethodHost::ptr> _method_hosts;
            Requestor::ptr _requestor;
        };
    }
}
